1. Field of the Invention
The present invention relates to electrical connectors, and more particularly to a land grid array (LGA) connector for electrically connecting an electronic package such as a CPU chip, to a circuit substrate such as a printed circuit board (PCB).
2. Description of the Prior Art
LGA connectors are commonly used in personal computer (PC) systems, for electrically connecting CPU chips to PCBs. This kind of connectors can avoid soldering procedures during being mounted on the PCBs.
FIG. 4 shows such a conventional LGA connector. The LGA connector comprises an insulative housing 2′ receiving a plurality of contacts (not shown) therein, a stiffener 4′ attached to the housing 2′, a load plate 5′ and a lever 6′ pivotally mounted to opposite sides of the housing 2′ respectively. The housing 2′ comprises a floor 20′, two opposite first sidewalls 24′ and two opposite second sidewalls 26′ adjacent the first sidewalls 24′. A plurality of passageways 22′ is defined in the floor 20′, for receiving the contacts therein. The contacts each protrude outwardly from a top portion of the housing 2′, for connecting with corresponding contact pads (not shown) of a CPU chip 3′. The first sidewalls 24′ each define a plurality of alternate protrusions 240′ and grooves 242′. Bosses 262′, 264′ are respectively formed on the second sidewalls 26′, for positioning and keying the CPU chip 3′ in the housing 2′. Notches 32′, 34′ are defined in the CPU chip 3′, for interferingly engaging with the bosses 265′, 266′ of the housing 2′. The CPU chip 3′ is, thereby, retained in the housing 2′. A step 263′ is formed at place the floor 20′ connecting with the second sidewalls 26′, for supporting two opposite sides of the CPU chip 3′ thereon.
In use, the CPU chip 3′ is disposed on the housing 2′. The load plate 5′ is pressed down onto the CPU chip 3′, pressing portions (not numbered) of the load plate 5′ resting on the CPU chip 3′. The lever 6′ is rotated down to engage with one side of the load plate 5′, urging the pressing portion of the load plate 5′ to press on the CPU chip 3′.
When the lever 6′ presses down on the load plate 5′, the pressing portions of the load plate 5′ push down on the CPU chip 3′. Because the load plate 5′ urges against one side of the CPU chip 3′ near the load plate 5′ engaging with the stiffener 4′, the opposite side of the CPU chip 3′ is liable to be bent upwardly. As a result, warp or even horizontal displacement of the CPU chip 3′ occurs as the opposite side being pressed down finally. During insertion of the CPU chip 3′ into the housing 2′, the opposite side of the CPU chip is prone to scrape a corresponding second sidewall 26′ of the housing 2′. This can bring damage to effective electrical connection between the CPU chip 3′ and the contacts.
Referring also to FIGS. 5 and 6, the CPU chip 3′ is slantwise positioned in the housing 2′, one side of the CPU chip 3′ resting on the step 263′ and sharp-angle 362 of the opposite side abutting against a correspond second sidewall 26′. When the lever 6′ is rotated down to press on the load plate 5′, the pressing portion of the load plate 5′ pushing down on the CPU chip 3′. Then the CPU chip 3′ moves downwardly under the pressing force of the load plate 5′ applied by the lever 6′, sides of the CPU chip 3′ near the second sidewalls 26 abutting against and urging inner surfaces of the corresponding second sidewalls 26. Accordingly, scraping of the inner surfaces of the second sidewalls 26′ happens. Similarly, said scraping happens on inner surfaces of the first sidewalls 24′ and the CPU chip 3′ per se. As a result, parts of the inner surfaces of the sidewalls 24′, 26′ and the CPU chip 3′ scraped-away particulates are scraped away. The scraped-away particulates are prone to drop on the floor 20′ of the housing 2′, blocking up the CPU chip 3′ upwardly. This adversely can effect the firm connection between the CPU chip 3′ and the contacts near the scraped-away particulates. As a result, reliability of the electrical connection between the CPU chip 3′ and the contacts of the housing 2′ is accordingly decreased.
Therefore, a new land grid array electrical connector which overcomes the above-mentioned disadvantages of the prior art is desired.